The present invention relates to a three-position enable switch which sequentially switches a contact mechanism of its own from an OFF state to an ON state and again to the OFF state according to the position of a manipulation member in a specific direction of its operation. More particularly, the invention is concerned with an enable switch suited for a portable operator panel used for teaching an industrial robot, for example.
Conventionally, there exist commercially available three-position enable switches which permit a manipulation member to sequentially stop at a non-operated position, an intermediate stop position and a fully operated position as operated in a particular direction of operation with a finger of the hand, wherein a contact mechanism is set to an OFF state when the manipulation member is not operated and held at the non-operated position, the contact mechanism is set to an ON state when the manipulation member is operated up to the intermediate stop position, and the contact mechanism is again set to the OFF state when the manipulation member is further operated up to the fully operated position. The enable switches of this kind are provided on a portable operator panel used for teaching an industrial robot, for example, to ensure operator safety.
Specifically, a portable operator panel 401 connected to a control apparatus for controlling a robot is provided with enable switches 411a, 411b together with manipulation switches 409a, 409b, etc. corresponding to various motions of the robot, as shown in FIGS. 5 and 6. Operation of the individual manipulation switches 409a, 409b, etc. is enabled when the enable switches 411a, 411b are under conditions where their manipulation members have been operated to the intermediate stop position, that is, when contact mechanisms of the enable switches 411a, 411b are in the ON state. On the other hand, operation of the individual manipulation switches, etc. is disabled when the enable switches 411a, 411b are under conditions where their manipulation members are at the non-operated or fully operated position, that is, when the contact mechanisms of the enable switches 411a, 411b are in the OFF state.
With this arrangement, if the robot makes a motion unintended by the operator due to misoperation of a manipulation switch, for instance, when the operator is setting the robot into motion by manipulating the manipulation switch while operating the manipulation member of an enable switch, it is possible to set the contact mechanism of the enable switch to the OFF state and instantly stop the motion of the robot regardless of the operating state of the manipulation switch by letting the finger of the hand away from the manipulation member of the enable switch or by tightly pressing the manipulation member further from the intermediate stop position to the fully operated position.
When operating a portable operator panel, the operator normally holds it from its side with its front side on which the manipulation switches, etc. are arranged oriented frontward so that the operator can easily observe the manipulation switches, etc. with the eyes. Particularly when operating a large-sized portable operator panel, the operator holds it from both sides. To operate the robot through the portable operator panel, the operator has to operate not only the manipulation switches, etc. as stated above but also the enable switches at the same time while holding the portable operator panel.
Thus, taking into consideration the operability of the portable operator panel, the enable switches should be arranged on the portable operator panel in such a manner that its manipulation members are located in an area where fingers of the operator""s hand holding the portable operator panel can be positioned face to face with the manipulation members. If the manipulation members are so arranged, the operator can press the manipulation members of the enable switches by using his or her fingers placed face to face with the manipulation members from the rear side of the panel among the fingers holding the portable operator panel from its side.
In the conventional enable switch, however, the manipulation member is provided in such a manner that it shifts generally along a straight line connecting the non-operated position to the fully operated position via the intermediate stop position, and a surface of the manipulation member with which a finger of the hand comes into contact moves in a position generally parallel to the panel surface when the manipulation member is depressed. For this reason, movement of the surface of the manipulation member with which the finger of the hand is in contact does not conform to the swing motion of the finger about its joint produced when the finger facing the manipulation member presses the manipulation member with the hand holding the portable operator panel from its side. Therefore, operability of the manipulation member is poor, and this makes it impossible in certain cases to exactly move the manipulation member in the event of an emergency stop which requires an immediate action to be taken. Also, to smoothly move the manipulation member of the conventional enable switch along the straight line over a relatively large stroke from the non-operated position to the fully operated position via the intermediate stop position, it is inevitable to make some clearance between outside surfaces of the manipulation member and a guide member in a direction perpendicular to its moving direction. For this reason, the manipulation member tends to be inclined with respect to its moving direction. As a consequence, if multiple contact mechanisms are provided to achieve enhanced safety, there might arise a case where ON/OFF states of the multiple contact mechanisms could not be switched at the same time by a single manipulation member.
Furthermore, there exist no conventional enable switches which have been designed with ease of installation on a portable operator panel in mind. Thus, it has not been possible to easily install the conventional enable switches produced as separate components, resulting in a problem that the conventional enable switches would make the process of manufacturing the portable operator panel rather complex.
Accordingly, it is an object of the invention to provide an enable switch which makes it possible to exactly move a manipulation member with improved operability in the event of an emergency stop which requires an immediate action by adapting the movement of a surface of the manipulation member in contact with a finger of the hand holding a portable operator panel from its side, for instance, to the motion of the finger facing the rear side of the panel, achieve an improvement in safety by providing multiple contact mechanisms in such a manner that the ON/OFF states of the multiple contact mechanisms can be switched at the same time by moving a single manipulation member, and simplify the process of manufacturing the portable operator panel by making it possible to easily install the enable switch produced as a separate component on the portable operator panel.
The present invention employs the following constructions as means for solving the aforementioned problems.
According to the present invention, an enable switch provided with a contact mechanism having a movable contact which is biased toward an OFF state switches the contact mechanism between its ON and OFF states during a period when a manipulation member moves from a non-operated position to an intermediate stop position and during a period when the manipulation member moves from the intermediate stop position to a fully operated position. The enable switch is characterized in that it is provided with a motion transmission mechanism including a first elastic member of which one end swingably supports the manipulation member in a housing and biases the manipulation member toward the non-operated position in such a manner that part of the manipulation member is exposed to the exterior, wherein the motion transmission mechanism converts a swing motion of the manipulation member from the non-operated position to the intermediate stop position into a motion of switching from the OFF state to the ON state and transmits this switching motion to the contact mechanism, converts a swing motion of the manipulation member from the intermediate stop position to the fully operated position into a motion of switching from the ON state to the OFF state and transmits this switching motion to the contact mechanism, and prohibits transmission of the swing motion of the manipulation member to the contact mechanism during a period when the manipulation member returns from the fully operated position back to the non-operated position.
In this construction, when the manipulation member is pressed against an elastic force exerted by the first elastic member, the manipulation member swings from the non-operated position to the fully operated position via the intermediate stop position. This swing motion of the manipulation member from the non-operated position to the intermediate stop position is transmitted to the contact mechanism via the motion transmission mechanism, whereby the contact mechanism is switched from the OFF state to the ON state. Also, the swing motion of the manipulation member from the intermediate stop position to the fully operated position is transmitted to the contact mechanism via the motion transmission mechanism, whereby the contact mechanism is switched from the ON state to the OFF state. When a pushing force applied to the manipulation member is released and the manipulation member begins to move from the fully operated position back to the non-operated position, transmission of the swing motion of the manipulation member to the contact mechanism by the motion transmission mechanism is prohibited until the manipulation member returns to the non-operated position via the intermediate stop position next time, and the contact mechanism is held in the OFF state by a restoring force exerted on the movable contact.
Therefore, the manipulation member swings from the non-operated position up to the fully operated position via the intermediate stop position in conformity with the motion of a finger of an operator""s hand as the operator presses the manipulation member, and the contact mechanism is switched from the OFF state to the ON state during the period when the manipulation member moves from the non-operated position to the intermediate stop position. Also, the contact mechanism is switched from the ON state to the OFF state during the period when the manipulation member moves from the intermediate stop position to the fully operated position. Thereafter, the swing motion of the manipulation member is not transmitted to the contact mechanism until the manipulation member returns to the non-operated position, so that the OFF state of the contact mechanism, which was switched during the period when the manipulation member swung from the intermediate stop position to the fully operated position, is maintained until the manipulation member returns to the non-operated position next time.
Additionally, the enable switch is characterized in that the motion transmission mechanism further includes a transmission member which is supported by the manipulation member in such a manner that the transmission member can freely move between a transmitting position and a non-transmitting position located along the radial direction of an arc which is the trajectory of the swing motion of the manipulation member, a second elastic member which biases the transmission member toward its transmitting position, a contact member which is supported by the manipulation member in such a manner that the contact member can freely move between an exposed position and a retracted position located along a swing direction of the manipulation member and causes the transmission member to move from the transmitting position to the non-transmitting position during a period when the contact member moves from the exposed position to the retracted position, a third elastic member which biases the contact member toward its exposed position, a driven member which converts the swing motion of the manipulation member transmitted via the transmission member as it is located at the transmitting position into a swing motion of the movable contact, transmits this switching motion to the contact mechanism, and prohibits the transmission member from moving from the non-transmitting position to the transmitting position during the period when the manipulation member swings from the fully operated position to the non-operated position, and a restricting member which causes the contact member to move from the exposed position to the retracted position during the period when the manipulation member swings from the intermediate stop position to the fully operated position.
In this construction, the motion transmission mechanism for transmitting the swing motion of the manipulation member to the contact member includes the transmission member which is biased toward the transmitting position under conditions where the transmission member is supported in such a manner that it can freely move relative to the manipulation member between the transmitting position and the non-transmitting position located along the radial direction of the arc which is the trajectory of the swing motion of the manipulation member, the contact member which is biased toward the exposed position and causes the transmission member to move from the transmitting position to the non-transmitting position during the period when the contact member moves from the exposed position to the retracted position under conditions where the contact member is supported in such a manner that it can freely move relative to the manipulation member between the exposed position and the retracted position located along the swing direction of the manipulation member, and the driven member which converts the swing motion of the manipulation member transmitted via the transmission member as it is located at the transmitting position into the switching motion of the movable contact, transmits this switching motion to the contact mechanism, and prohibits the transmission member from moving from the non-transmitting position to the transmitting position during the period when the manipulation member swings from the fully operated position to the non-operated position.
Therefore, the transmission member is located at the transmitting position during the period when the manipulation member swings from non-operated position to the intermediate stop position, and the swing motion of the manipulation member is transmitted to the contact mechanism in the form of the switching motion of the movable contact via the transmission member and the driven member, whereby the contact mechanism is switched from the OFF state to the ON state. While moving from the exposed position to the retracted position, the contact member causes the transmission member to move up to the non-transmitting position during the period when the manipulation member swings from the intermediate stop position to the fully operated position as the contact member is in contact with the restricting member. Consequently, the swing motion of the manipulation member becomes nontransmittible to the contact mechanism, the movable contact of the contact mechanism returns to the state which existed before the commencement of the swing motion of the manipulation member due to the restoring force, and the contact mechanism is switched from the OFF state to the ON state. Since the driven member prohibits the transmission member from moving to the transmitting position during the period when the manipulation member swings from the fully operated position to the non-operated position, no swing motion of the manipulation member is transmitted to the contact mechanism and the contact mechanism is held in the OFF state to which the contact mechanism was switched when manipulation member reached the fully operated position.
Additionally, the enable switch is characterized in that only such part of the manipulation member located in the radial direction of its swing motion is exposed outward from the housing that a manipulating torque exerted on the manipulation member about its point of support is larger than the moment exerted by the first to third elastic members.
In this construction, the manipulating torque exerted by the finger of the operator""s hand on the part of the manipulation member exposed outward from the housing is always larger than the moment of the elastic force biasing the contact member toward its exposed position. Therefore, the manipulation member moves up to the fully operated position against the elastic force acting on the contact member as a result of operation of the manipulation member with the finger of the operator""s hand.
Additionally, the enable switch is characterized in that multiple contact mechanisms are arranged side by side in a direction perpendicular to the radial direction of the arc which is the trajectory of the swing motion of the manipulation member.
In this construction, the multiple contact mechanisms are arranged side by side in the direction perpendicular to the radial direction of the arc which is the trajectory of the swing motion of the manipulation member. The manipulation member smoothly swings about the point of support located at its one end with certainty without being inclined with respect to the swing direction. Therefore, the manipulation member does not produce during its swing motion any inclination with respect to the direction perpendicular to the radial direction of the arc which is the trajectory of the swing motion of the manipulation member, and the movable contacts of the multiple contact mechanisms joined to this portion always function in the same condition.
Additionally, the enable switch is characterized in that a cylindrical compartment is formed projectingly from a flat surface of the housing on its side opposite to the side where the manipulation member is exposed to the exterior, and the contact mechanism is accommodated in this compartment.
In this construction, the contact mechanism is accommodated in the compartment projecting from the flat surface of the housing on its side opposite to the side where the manipulation member is exposed to the exterior. Therefore, the contact mechanism is disposed on the inside of an apparatus, such as a portable operator panel, on which the enable switch should be installed if the cylindrical compartment is fitted in a hole formed in the apparatus.